Skills for Life is often seen as one the great educational triumphs of the past decade. Reaching six million people failed by compulsory schooling, the scheme has helped 2.8 million earn qualifications, many of them for the first time.
But a new study suggests that in one important respect it has been an utter failure: the pound;1 billion-a-year programme has not had any measurable effect on the chances of adult students who leave colleges with a basic skills qualification getting a job or increasing their earnings.
Researchers following the progress of more than 2,000 basic skills students over three years could find no statistically significant link between their literacy and numeracy qualifications and increased chances of higher earnings after comparing them with a similar group not on the courses.
Announcing the research, the Department of Business, Innovation and Skills (BIS) said Skills for Life changes people for the better in almost every way - but there was no mention of any economic benefits.
"Today, BIS publishes further research evidence which shows that taking a literacy or numeracy course at college can improve adults' self-esteem, their health, increase their independence and improves their ability to conduct a wide range of everyday activities," the department said. "It can also set adults on the path to further learning."
While these benefits are undoubtedly real, a department now so focused on industry and employability can only have been disappointed at the lack of economic impact.
Softening the blow was another report, commissioned after the longitudinal study, which reviewed the evidence around basic skills and their impact on employability and earnings. This found improvements in earnings and employment for adults gaining literacy and numeracy skills, although some effects were weak. But with almost all the other research examining cohorts before Skills for Life was in place, only the most recent study puts the current method of teaching under the microscope.
It marked the 10-year anniversary of the Moser report, which outlined the scale of the problem in adult literacy and numeracy, and laid the foundations for the launch of Skills for Life in 2001.
Lord Moser said about a fifth of adults, or seven million people, have problems with functional literacy and numeracy.
Later surveys found the problem was particularly widespread in numeracy, where just under half of adults have skills below level 1, meaning they struggle to understand straightforward mathematical information, or to pick out relevant information from graphs or tables.
Achieving functional literacy and numeracy is seen as the great divide between haves and have-nots in the job market: about half of people without functional literacy are out of work, whereas three-quarters of those with good literacy skills have jobs.
So if it is well-established that a lack of basic skills harms an individual's chance of employment, why has teaching people literacy and numeracy in Skills for Life not yet helped them into work?
Carol Taylor, director of operations at Niace, the adult education body, said that the prime motivation for promoting literacy skills should not be economic.
"I don't think that literacy is primarily about economics," she said. "It's about democracy and it's about a fundamental human right like having enough water to drink."
However, she conceded that there were issues with the way Skills for Life has been delivered, in particular the two or three hours' teaching a week for 20 or 30 weeks. She said that apprenticeships, by contrast, were successful because students were completely immersed in the work. Similarly, she said, English for speakers of other languages has also been more effective when it is more intensive.
But if Skills for Life is not succeeding in delivering employees ready for the workplace, surely employers are up in arms about the workers they hire with literacy and numeracy qualifications that have no value in terms of enhancing employability?
This does not seem to be the case. The Confederation of British Industry (CBI) has been extremely vocal about poor literacy and numeracy skills and the harm they do to British business, but there have been no complaints that Skills for Life is ineffective.
Simon Nathan, senior policy officer for the CBI, said: "We published a survey on this, which found that two-fifths of employers say they have concerns about literacy and numeracy skills, and lots of studies on how much that loses businesses.
"We want to see people leaving schools with these skills. But we haven't got specific concerns about Skills for Life."
The survey itself offers several possibilities why no economic benefit was detected. It notes that Skills for Life has evolved and its study looked at students in 2003, 2004 and 2005.
Since then, there has been greater integration with vocational courses and the beginnings of an increased focus on numeracy, which has been identified as the greater problem and which may have greater value for some employers.
Unfortunately, in an ever-changing policy environment, by the time research is complete the situation has invariably changed. And policy changes frequently fail to eradicate the issues uncovered by research.
For example, the employer training pilots were found to be full of "dead weight" training that businesses would have paid for themselves. Despite assurances that changes to Train to Gain would put an end to this, later studies found that it persisted. But perhaps it simply takes longer for years or decades of disadvantage to be undone.
Ms Taylor said: "If you really want to measure economic impact, you need to look at whole generations."
Adults who have picked up basic skills will have improved their children's chances of success, she said. However, some of the other studies identified in the summary of research on basic skills and employment set an expectation of a quicker rate of return, with one US study detecting improvements within three years of achieving qualifications.
The cohort under the microscope in this research also had the benefit of boom times in the economy. Perhaps even then they were crowded out by workers with long-established skills.
But it will only get harder for them now - and harder for Skills for Life to show that it can mean skills for jobs as well.